This invention relates to a paper folding device.
There is known a paper folding device comprising a pair of parallel wings arranged face to face across a small gap of a width enough for a sheet of paper to enter into, with a stopper disposed in the gap in such a manner that the stopper can be displaced in the direction of insertion of the paper into the gap.
When the forward edge of the sheet of paper entering the gap hits the stopper inside the gap, the sheet cannot advance farther into the gap but the middle portion of the sheet adjacent the entrance opening of the gap is bent, and the bent portion comes to be nipped by a pair of nip rollers arranged adjacent the entrance opening of the gap, so that the sheet of paper is folded into two portions as it is passed through the nip rollers. The shape of the folded sheet of paper depends upon the position of the stopper or the distance between the stopper and the entrance of the gap.
In the paper folding device of the above-mentioned type, since the sheet of paper to be folded is fed at a high speed, a very big noise is caused by the forward edge of the sheet striking the stopper. Particularly in a high-speed paper folding machine, the sheet runs at a high speed with a short cycle of feeding, so that the above-mentioned striking sound is very high and is repeated continuously in a short cycle. The sound is so high that it is almost impossible to hear ordinary human voice adjacent the running machine. Therefore, it is required that the device should be provided with means for soundproofing. To meet the requirement, it has been proposed to put the whole paper folding device in a soundproof box and tightly close the opening of the box by a cover. Indeed the arrangement is effective in sound isolation. However, if the position of the stopper is to be adjusted in order to fold a sheet of paper into a different pattern, it is necessary to take the paper folding device out of the soundproof box and change the position of the stopper and then again put the device into the box. This is very troublesome and time-consuming. Similarly, whenever the gap in the device is stuffed with paper, the device must be taken out of the soundproof box for removing the paper from the gap.